typeCast is up to 10x slower #889
Description
When the typeCast option is used, queries tend to run up to 10x slower under load. A perf profile shows that most of the additional time is spent in column_defintion.js obtaining the schema and table name in the code below:
const addString = function(name) {
Object.defineProperty(ColumnDefinition.prototype, name, {
get: function() {
const start = this['_' + name + 'Start'];
const end = start + this['_' + name + 'Length'];
return StringParser.decode(
this._buf.slice(start, end),
this.encoding === 'binary' ? this._clientEncoding : this.encoding
);
}
});
};
These fields are meant to be computed lazily, but end up getting recomputed for every field access as part of the 'wrap' function implementation that needs field.schema, field.table and field.name
function wrap(field, type, packet, encoding) {
return {
type: type,
length: field.columnLength,
db: field.schema,
table: field.table,
name: field.name,
string: function() {
return packet.readLengthCodedString(encoding);
},
buffer: function() {
return packet.readLengthCodedBuffer();
},
geometry: function() {
return packet.parseGeometryValue();
}
};
}
Given that these fields are used for every column, can these be precomputed?